Use GrConvexPolyEffect when clip is a single convex polygon

BUG=skia:2051

Committed: http://code.google.com/p/skia/source/detail?r=13286

R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/151523005

git-svn-id: http://skia.googlecode.com/svn/trunk@13306 2bbb7eff-a529-9590-31e7-b0007b416f81

4 files changed, 33 insertions, 4 deletions

diff --git a/expectations/gm/ignored-tests.txt b/expectations/gm/ignored-tests.txt
index cf708c836d..2e3afd7918 100644
--- a/expectations/gm/ignored-tests.txt
+++ b/expectations/gm/ignored-tests.txt
@@ -31,4 +31,7 @@
 ## Added by epoger as part of MADE-UP BUG
 ## https://code.google.com/p/skia/issues/detail?id=123456 : ignoring failures on
 ## gradtext GM test
-#gradtext
\ No newline at end of file
+#gradtext
+
+# Added by bsalomon for skbug.com/2051, https://codereview.chromium.org/151523005
+filltypespersp
diff --git a/src/gpu/GrClipMaskManager.cpp b/src/gpu/GrClipMaskManager.cpp
index 4fd746f3fa..340ede0d31 100644
--- a/src/gpu/GrClipMaskManager.cpp
+++ b/src/gpu/GrClipMaskManager.cpp
@@ -18,6 +18,7 @@
 #include "GrStencilBuffer.h"
 #include "GrSWMaskHelper.h"
 #include "effects/GrTextureDomain.h"
+#include "effects/GrConvexPolyEffect.h"
 #include "SkRasterClip.h"
 #include "SkStrokeRec.h"
 #include "SkTLazy.h"
@@ -153,9 +154,33 @@ bool GrClipMaskManager::setupClipping(const GrClipData* clipDataIn,
         return true;
     }
 
-#if GR_AA_CLIP
-    // TODO: catch isRect && requiresAA and use clip planes if available rather than a mask.
+    // If there is only one clip element and it is a convex polygon we just install an effect that
+    // clips against the edges.
+    if (1 == elements.count() && SkClipStack::Element::kPath_Type == elements.tail()->getType() &&
+        SkRegion::kReplace_Op == elements.tail()->getOp()) {
+        const SkPath& p = elements.tail()->getPath();
+        bool isAA = GR_AA_CLIP && elements.tail()->isAA();
+        SkAutoTUnref<GrEffectRef> effect;
+        if (rt->isMultisampled()) {
+            // A coverage effect for AA clipping won't play nicely with MSAA.
+            if (!isAA) {
+                effect.reset(GrConvexPolyEffect::Create(GrConvexPolyEffect::kFillNoAA_EdgeType, p));
+            }
+        } else {
+            GrConvexPolyEffect::EdgeType type = isAA ? GrConvexPolyEffect::kFillAA_EdgeType :
+                                                       GrConvexPolyEffect::kFillNoAA_EdgeType;
+            effect.reset(GrConvexPolyEffect::Create(type, p));
+        }
+        if (effect) {
+            are->set(fGpu->drawState());
+            fGpu->drawState()->addCoverageEffect(effect);
+            fGpu->disableScissor();
+            this->setGpuStencil();
+            return true;
+        }
+    }
 
+#if GR_AA_CLIP
     // If MSAA is enabled we can do everything in the stencil buffer.
     if (0 == rt->numSamples() && requiresAA) {
         GrTexture* result = NULL;
diff --git a/src/gpu/effects/GrConvexPolyEffect.cpp b/src/gpu/effects/GrConvexPolyEffect.cpp
index 4616bdb7a3..e47ed0f866 100644
--- a/src/gpu/effects/GrConvexPolyEffect.cpp
+++ b/src/gpu/effects/GrConvexPolyEffect.cpp
@@ -174,7 +174,7 @@ GrEffectRef* GrConvexPolyEffect::TestCreate(SkRandom* random,
                                             const GrDrawTargetCaps& caps,
                                             GrTexture*[]) {
     EdgeType edgeType = static_cast<EdgeType>(random->nextULessThan(kEdgeTypeCnt));
-    int count = random->nextULessThan(kMaxEdges + 1);
+    int count = random->nextULessThan(kMaxEdges) + 1;
     SkScalar edges[kMaxEdges * 3];
     for (int i = 0; i < 3 * count; ++i) {
         edges[i] = random->nextSScalar1();
diff --git a/tests/GLProgramsTest.cpp b/tests/GLProgramsTest.cpp
index 6c4aace96f..f3207352df 100644
--- a/tests/GLProgramsTest.cpp
+++ b/tests/GLProgramsTest.cpp
@@ -173,6 +173,7 @@ bool GrGpuGL::programUnitTest(int maxStages) {
                                                                             this->getContext(),
                                                                             *this->caps(),
                                                                             dummyTextures));
+            SkASSERT(effect);
             int numAttribs = (*effect)->numVertexAttribs();
 
             // If adding this effect would exceed the max attrib count then generate a